Urban Flooding Mitigation in Bergen
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EXCURSION GUIDE URBAN FLOODING MITIGATION IN BERGEN Date: May 13th INTRODUCTION SCHEDULE 07:30 Meet at Bergen Bryggen hotel The cable car Fløibanen will take us to the viewpoint Fløyen, where the Municipality of Bergen and the 08:00-08:30 Cable car to Fløyen Chief of Emergency Management will give a lecture. Focus will be on risk and emergency management 08:30-09:30 Lecture on Fløyen connected to surface water in the city of Bergen. 09:30-11:30 Walk: Starefossen & Svartediket From Fløyen we will walk to Starefossen. This is a location where a small river runs into the settlement. 11:30-13:30 Lunch at Troldhaugen The river causes trouble during all heavy rain 14:00-15:30 Guided walk Bryggen in Bergen periods. From Starefossen we will walk to Svartediket, the drinking water reservoir of Bergen, where we will talk about a Forest protection project. We will have lunch at Troldhaugen, the home of the famous Norwegian composer Edvard Grieg. The Directorate for Cultural Heritage will give a guided walk, concerning safeguarding the world heritage site of Bryggen in Bergen. 14th Congress INTERPRAEVENT 2020 2 / 10 Location 1: Fløyen FLØIBANEN Fløibanen is a cable car that runs from the center of Bergen to the viewpoint Fløyen (figure 1). There are two carriages attached to a cable, which are driven by two large drive wheels located in the engine room at Fløibanen's upper station. The flow paths run on electricity and are led by the carriage driver. Fløibanen opened in 1918. It is Bergen's most visited tourist attraction. In addition, the Fløibanen is the natural means of transport for the residents along the mountain side and the kindergartens on Fløyen. Figure 2. Master Plan for Storm Water Figure 1. Restaurant on Fløyen (Municipality (Municipality of Bergen). of Bergen). “RISK AND EMERGENCY MANAGEMENT IN THE CITY OF BERGEN” The chief of emergency management / Municipality of Bergen will give a lecture about Bergen’s risk and emergency management. Bergen Water and Sewerage department will give an introduction to the municipality’s Master plan for Storm Water (figure 2). Starefossen is given as an example of how Bergen municipality work with issues connected to surface water management. 14th Congress INTERPRAEVENT 2020 3 / 10 Location 2: Starefossen AN EXAMPLE OF RUN-OFF MANAGEMENT IN BERGEN Starefossen is a smaller watercourse that runs through older city areas (figure 3). During heavy rainfall, the watercourse regularly goes over its banks, finding new paths and causing damage – to the inhabitants' great frustration. Figure 3. Starefossen (Municipality of Bergen). The situation is not new: Because the responsibility and ownerships along the watercourse is divided between many different institutions/people, little has been done to improve. The City of Bergen will now take the overall responsibility for the watercourse. Figure 4. Walking route. This means figuring out possible measures, giving orders to private and public actors, and implementing measures under municipal auspices cannot place responsibility on others. 14th Congress INTERPRAEVENT 2020 4 / 10 Location 3: Svartediket AVALANCHE AND FOREST Just after the Second World War Norwegian spruce, and to some extent Sitka spruce and other foreign tree species, where planted with high enthusiasm. With plenty of available space, huge subsidies, but limited knowledge the forest administration motivated the landowners to plant. Some of these forests were planted in steep slopes without infrastructure. This forest does today set the agenda for much of the debate about mitigation forest in Norway. Many municipalities in western Norway see the need for to use the forest to mitigate natural disasters. Figure 6. Forest around Svartediket (NVE). Still, the logging volume has been rising the latest years and the clear cuts have increased in size. The Agency for Water and Sewerage Works in Bergen municipalities are facing many questions; choice of municipality see nature based solutions as a tree species after logging, how to convert a possible way of solving important public obligations. monoculture forest into a more varied and stabile They aim to test natural solutions that are cost forest (figure 5). Another issue is how to establish efficient compared to traditional technical mitigation new forest roads without causing trouble. measures. Forest management, tree species mixture and logging types can both improve or reduce the forest’s function as protection. Forest management, natural regeneration or banning large clear cuts would not prevent the forest owners from making a profit, but would call for more forest competence. Until today, there has been little focus on integrating natural resource management in communal planning. Particularly in western Norway, the aim of the forest industry production of the biggest volume per hectare productive forest area. This shifts the activity towards the planted spruce areas, while the remaining area of fir and leaf woods see little activity. Figure 5. Monoculture (a) vs a more varied and stable forest (b) (Norwegian Water Resources A holistic area planning and ecosystem based and Energy Directorate, NVE). management can reinforce the ecosystem’s services. Forest as a natural ecosystem work as a A clear legislation, smart delineation of important buffer against floods, reduce runoff, depletion of areas and good examples of forest management are nutrients and prevents 500-600 mm rainfall reaching missing in areas where forests are important for ground yearly (by interception), binding earth mitigating natural hazards. particles and clean air and water, particularly in urban areas. Bergen city has chosen to be a pilot municipality in looking for practical solutions in some areas. The Svartediket valley, water supply source for the City of Bergen, is one of these areas (figure 6). 14th Congress INTERPRAEVENT 2020 5 / 10 PROJECT GOALS The aim of the project is to make an overview of possible mitigating measures, and find necessary solutions to reduce natural hazards in areas where forests have considerable importance in protection. The project will also aim to put forests in a financial context, increase risk knowledge, and show synergies related to forest management. And, at last, investigate the need for changes in forest management methods. ACTIVITIES - Multidisciplinary discussions in field - Expert exchange with forest management services from Bavaria and Switzerland - Cost/benefit analysis in collaboration with Norwegian Institute of Bioeconomy Research (NIBIO). - The Bergen forest and tree planting company, in collaboration with the County Governor of Vestland, wrote a note for the company board and Bergen municipality. - Planning logging with cable crane in a demo stand. Primarily to prevent clear cuts, but also to facilitate natural regeneration and stabilizing tree species. - Conduct logging in winter of 2019/2020. 14th Congress INTERPRAEVENT 2020 6 / 10 Lunch: Troldhaugen Troldhaugen was the home of Nina and Edvard Grieg. Edvard Grieg, from Bergen, was a famous Norwegian composer and pianist. One of Edvard Griegs most known works is “I Dovregubben’s hall” (“In hall of the Mountain King”) from the play “Peer Gynt”, made by Henrik Ibsen. He used and developed Norwegian folk music in his own way, and thereby brought the music of Norway to the world, and also developed a national identity for Norwegians. The Villa Troldhaugen was built in 1885, beautifully situated by Nordås Lake. From 1928 Troldhaugen has been a museum. The concert hall Troldhaugen Figure 7. Troldhaugen (Svein-Magne Tunli). is used for extended concert activities with its excellent acoustics. Griegs own piano from 1892 is often used. Reed more about Troldhaugen and Edvard Grieg at http://griegmuseum.no/en. 14th Congress INTERPRAEVENT 2020 7 / 10 Location 4: Bryggen SAFEGUARDING THE WORLD HERITAGE SITE OF BRYGGEN IN BERGEN The Directorate for Cultural Heritage will give a guided walk along Bryggen in Bergen and give an overview of an ongoing monitoring project as well as general history about the old buildings (figure 7). The standing buildings, which were built after the fire in 1702, rest on archaeological deposits up to 10 meters thick materials, rich in organic content. The deposits consist of the remains of previous settlements and the people who lived and worked there from the 11th century. Surveying of the buildings at Bryggen showed that Figure 7. Bryggen in Bergen (Municipality of there was considerable subsidence damage. Bergen). The rate of settling was so high that there was a need to find the reason for this. The purpose was to initiate mitigation measures to reduce the subsidence. Groundwater and surface water is a prerequisite for ensuring that the rich organic cultural layers can be safeguarded and provide stable ground conditions for the buildings above. Sinking groundwater allows free access to air and microbes, and the organic deposits decay. A surface-water infiltration system has been established to ensure sufficient groundwater levels in the cultural deposits. In addition to perforated pipes in trenches, the system consists of rainwater gardens and swales in the park at the rear of Bryggen (figure 8). Figure 8. Rain Garden behind Bryggen in Bergen (Municipality of Bergen). 14th Congress INTERPRAEVENT 2020 8 / 10 Authors Hanne Merete Moldung (The Directorate for Cultural Heritage) Hogne Hjelle (Municipality of Bergen) Odd Are Jensen (NVE) Simon Wolff (Municipality of Bjørnafjorden) Front: High sea level at Bryggen in Bergen, Arthur Gebuys/Alamy Stock Photo. 14th Congress INTERPRAEVENT 2020 9 / 10 Notes 14th Congress INTERPRAEVENT 2020 10 / 10 .